Background Although pyrethroids are known for low toxicity to humans, clinical systemic characteristics of pyrethroid poisoning remain undefined. We investigated atypical presentations of pyrethroid poisoning and the predictors, among those readily assessed in the emergency department.

Methods 59 pyrethroid poisoning cases that were diagnosed and treated at the emergency department of Wonju Severance Christian Hospital from September 2004 to December 2012 were retrospectively reviewed.

Results Atypical presentations were seen in 22 patients (39.3%). Atypical presentations after pyrethroid poisoning included respiratory failure requiring ventilator care (10 patients, 17.9%), hypotension (systolic blood pressure <90 mm Hg) (6 patients, 10.7%), pneumonia (4 patients, 7.1%), acute kidney injury (6 patients, 10.7%), Glasgow Coma Scale (GCS) <15 (19 patients, 33.9%), seizure (2 patients, 3.6%) and death (2 patients, 3.6%). There were differences between atypical versus typical groups in terms of age (62.1±3.7 vs 51.0±2.9, p=0.020), ingested amounts (300 (IQR 100–338) cc vs 100 (IQR 50–300) cc, p=0.002), and bicarbonate and serum lactate (17.4±1.1 vs 20.5±0.4, p=0.011; and 4.42 (IQR 3.60–7.91) mmol/L vs 3.01 (IQR 2.16–4.73) mmol/L, p=0.010, respectively) in initial arterial blood gas analysis. Predictors of the atypical presentations were ingested amount and serum lactate ((OR 1.004, 95% CI 1.001 to 1.008, p=0.013) and (OR 1.387, CI 1.074 to 1.791, p=0.012), respectively). The optimal points were 250 cc and 3.5 mmol/dL.

Conclusions 39.3% of pyrethroid poisoned patients had atypical presentations with the most common being respiratory failure requiring ventilator care. Predictors of atypical presentation were ingested amount >250 cc and serum lactate >3.5 mmol/L.